1. Field of the Invention
The present invention relates generally to masts and, more specifically, to a telescopic mast system.
2. Description of the Related Art
It is known to provide a telescopic mast to raise or lower an object such as a communication device, e.g., a surveillance camera. Typically, the telescopic mast includes a plurality of tubular mast sections that may be raised by air or cable power. In the air powered telescopic mast, air is supplied from a source to a pneumatic cylinder that raises the mast sections and when the air is discontinued to the pneumatic cylinder, gravity allows the mast sections to be lowered. In the cable powered telescopic mast, a winch and pulley is used with a cable to raise the mast sections and gravity is allows the mast sections to be lowered.
One disadvantage of the air powered telescopic mast is that if wind bends the mast such that there is lateral deflection, air will leak out between the mast sections. The same results can occur if a bullet hole or other type of shrapnel punctures the cylinder. As a result, the mast will lose pressure and not stay in the raised position. Another disadvantage is that the telescopic mast cannot be brought down quickly. Additionally, speed in lowering the mast is an important factor because these telescopic masts typically have expensive equipment such as a communication device mounted on top of the mast and, in a hostile environment, need to be lowered quickly. The current systems lower by gravity, and can bind due to dirt or ice. Another disadvantage of the air powered telescopic mast is that it can only support a low capacity load due to the small piston of the pneumatic cylinder.
One disadvantage of the cable powered telescopic mast is that it can only support a low capacity load because of the multiple mast sections, otherwise the cable becomes thick. Another disadvantage of the cable powered telescopic mast is that there is no control of speed in lowering the mast because the mast relies on gravity to be lowered. In addition, foreign objects such as ice or sand causes interference with the mast sections and the mast will not lower itself due to gravity. The current systems lower by gravity, and can bind due to dirt or ice.
Therefore, it is desirable to provide a telescopic mast system that is powered or driven and allows the mast to be raised and lowered relatively quickly. It is also desirable to provide a telescopic mast system that allow the mast to support a relatively high capacity load. It is further desirable to provide a telescopic mast system that can raise and lower a mast in hostile environments and is not affected by foreign objects such as ice and sand. Thus, there is a need in the art to provide a telescopic mast system that meets at least one of these desires.